Metal reduction and combustion process



y 15, 1956 I T. H. OSTER 2,745,734

METAL REDUCTION AND COMBUSTION PROCESS Filed Oct. 30, 1951 THOMAS H. O5 75/? INVENTOR.

Motor Company, Dearborn, Mich a corporation of Delaware Application October 30, 1951, Serial No. 253,399 12 Claims. (Cl. 754i This invention is concerned with the art of utilizing fuels and more particularly with a process for the economical combustion of solid fuels which may well be high in very fusible ash and to simultaneously recover any metal values which may exist in the ash of the fuel or which may incidentally be added to the fuel.

As the supply of high grade fossil fuels in general and good coking coals in particular are becoming somewhat depleted it has become imperative from an economical standpoint to find suitable substitutes. Many of the more readily available fossil fuels are characterized by a high ash content and by the fact that this ash content exhibits a low fusion point. This combination of circumstances renders the combustion of these fuels difficult and ineificient in the ordinary type of coal burner due to the errosion of the brick work by molten slag and by the inevitable partial insulation of the heat absorbing surfaces of the boiler by the ash. In an effort to overcome these difiiculties the art has recently developed a fossil fuel burning device termed the horizontal cyclone burner.

Briefly, this device comprises a water cooled steel cylinder with its axis slightly inclined from the horizontal and provided at one end with means for the reception of a stream of crushed fuel and primary air and at the other end with an exit for the products of combustion. This type of burner and its operating characteristics are amply and ably described in an article entitled The Horizontal Cyclone Burner by A. E. Grunert, L. Skog and L. S. Wilcoxs'on, apearing' at page 613 et s'e'q., of the American Soicety of Mechanical Engineers, Transactions, volume 69, 1947.

It is the object of this invention to combine to improve the operation of this type of burner and to enable it to be used to recover metal values inherent in the ash of the fossil fuel, or deliberately added to the fuel stream. This invention is probably best understood by reference to the drawing which depicts a vertical section through a typical horizontal cyclone burner. In this drawing the horizontal steel shell is indicated generally at 10. This shell is protected over its entire inner surface with pipe coils 11 through which Water is circulated to protect refractory lining 12 and recover useful heat from the reactions occurring in the cyclone burner. One end of shell 19 terminates in an inlet 13 for the reception of crushed fuel and primary air. The opposite end of shell 13 terminates in re-entrant opening 14 designed to permit the escape of the products of combustion while at the same time inhibiting the loss of ash or slag. Immediately adjacent inlet 13 is a tangential opening 15 for the addition of secondary air under substantial pressure for a purpose Which will become apparent as the description proceeds. Molten material is released through slag discharge 16.

In the conventional operation of a burner of this type United States Patent a stream of coal, crushed to pass a Mi inch screen is permitted to flow into inlet 13 with a small stream of primary air. The bulk of the air needed for combustion of the fuel is injected through tangential opening 15 under a pressure of approximately 20 to 30 inches of water. This pressure combined with the tangential entrance of the secondary air stream is sufficient to cause the gases within the burner to rotate rapidly and to cause any given gas particle to describe a helical path in its travel from the inlet to the outlet of the burner. The interior of the burner is operated at a temperature sufliciently high to melt the ash produced. The particles of molten ash are hurled by centrifugal force against the peripheral Wall of the chamber and by virture of their sticky or viscous nature these molten particles coalesce to form a continuous coating thereover. Similarly particles of incompletely burned solid fuel are hurled against the walls of the chamber and trapped in this viscous slag layer and held there While they are completely coked and then consumed. During this burning time the slag layer and entrapped fuel particles continuously and slowly circulate around the periphery of the burner in a helical path and gradually advance toward the em't'. In conventional powerhouse practice the solid particles of fuel are completely consumed before the ash is discharged from the exit end as a molten slag. Practically all of the necessary combustion air is supplied to the burner as a combination of the primary and secondary air. The gaseous products of combustion are discharged from this burner into a boiler setting and there admixed with the remaining 15% of tertiary air to insure complete combustion. Similarly in powerhouse practice it is conventional to preheat the air employed for combustion by means of economizers heated by the stack gases leaving the boiler setting. Accordingly, these boilers are normally operated with air preheated to a temperature of between 306 and 5 degrees F. p u

The usual operation of this type of burner may be subjected to a substantial modification whereby the metal values inherent in the ash of the fuel may be recovered or metal ore may be added to the stream of solid fuel and the metal values recovered therefrom. While by no means so limited, this invention will be described primarily as adapted to the recovery of the iron content of coal ash and from iron ore or other ferruginous material added to the incoming solid fuel. In order to effect a substantial lowering in the level of oxidation of the ferric compounds either present in the coal ash or added as iron ore, it is essential that the burner be operated under substantial reducing conditions and the large volumes of combustible gasesso produced be burned with appropriate amounts of tertiary air after leaving the burner and entering the boiler setting. This can be accomplished either by increasing the amount of solid fuel fed to the system or by reducing the total of the primary and secondary air streams. if the conditions within the burner are maintained sumciently reducing it is possible to discharge along with the molten slag, iron either as molten iron or as a molten iron oxide or if desired, as the low melting eutectic of ferrous and ferric oxides. To obtain these results it is essential that at best only a minimum of carbon dioxide or water vapor be generated within the burner since at the operating temperature of the burner carbon dioxide and water vapor are decidedly oxidizing to iron and will in some concentration partially oxidize the lower oxides of iron.

Since the reduction of ferric compounds to the ferrous or elemental stage is a decidedly endothermic reaction and since the oxidation of carbon to carbon monoxide as opposed to the usual carbon dioxide is comparatively a much Weaker exothermic reaction it is essential that other means be employed to maintain the temperature of the interior of the cyclone burner at a value which will insure rapid and complete reaction and maintain the ash molten without the addition of excessive amounts of flux.

Recent technical advances have opened new methods of adding this essential heat to the burner chamber, The incoming air may be preheated well beyond powerhouse practice and sufliciently so that the heat so added plus the heat of combustion of the volatiles in the coal and the oxidation of the resultant coke to carbon monoxide will add sutficient heat to the process of combustion to insure the requisite temperature and to provide the energy demanded for the reduction of ferric compounds to iron or to the ferrous state. As an alternative to supplying all of the heat deficiency by heating the incoming air, the air 'five dollars per ton, has made such additions economically feasible. It is to be understood that the preheating of the incoming primary and secondary air or the enrichment of the incoming air with oxygen are not necessarily strictly alternative procedures, but may be employed simultaneously. In any event, conditions must be established which will dependably maintain the temperature of the interior of the burner well above the melting point of the particular slag being produced. It is further to be understood that the addition of more or less iron ore to the incoming fuel stream is a very potent tool for controlling the temperature of the reactor due to the highly endothermic nature of the iron reactions taking place Within the burner. Increasing amounts of secondary air will of course increase the temperature, but will hinder the iron reduction if employed in excess.

Any iron compound, usually an oxidic ore added to the coal stream meets the same fate as the fuel particles. The ore and fuel particles will be similarly entrapped in the viscous, helically flowing slag stream and while so entrapped, the fuel particles will be coked and at least par tially oxidized. Then the iron oxide particles will be reduced both by contact with the rapidly moving reducing gases and by reaction with the solid carbon. The precise degree to which the reduction of the iron compounds is to be carried out in the cyclone burner will be dictated by the economic conditions obtained at the particular installation under consideration. If the ash content of the coal is high, or its iron content is low, it will probably be found to be more economical to maintain highly reducing conditions in the cyclone burner and reduce the bulk of the iron compounds to metallic iron since the high ash content of the coal would result in a slag more dilute in iron compounds than is desired for a blast furnace charge. By completely reducing the iron compounds, the resultant molten iron may be separated from the supernatant slag by a simple gravity separation. This complete reduction necessitates an effluent gas rather low in carbon dioxide and water vapor and hence possessed of a high latent heating value. This gas should be burned immediately in a boiler or furnace setting adjacent the cyclone burner.

Under other circumstances as when coke is expensive, coal is cheap and blast furnace facilities are available, it may be more economical to permit the oxidation in the cyclone burner to be more complete and to discharge as a molten product either ferrous oxide or a mixture of ferrous and ferric oxides. If economical, burner conditions can readily be established and the thruput of the burner increased by discharging from the burner a molten oxide of iron carrying in suspension suflicient unconsumed but thoroughly coked fuel to give a product which may be charged into a conventional blast furnace without the addition in that machine of further coke for its reduction to pig iron.

It is desirable, if conditions anywhere within the cyclone burner are favorable to the production of elemental iron to limit the velocity of the helical flow of the gases to a value which will be insufficient to elevate such elemental iron from the bottom of the burner once it has formed there or descended there from other parts of the burner. A longitudinal trough running along the lowermost elements of the cylinder will assist materially in this separation. In this manner, the molten elemental iron will be protected from possible reoxidation by the supernatant layers of molten slag and unburned fuel and will promptly flow to slag discharge 16 and there be recovered. If necessary a separate tap hole 17 may be provided intermediate the ends of the cyclone burner for the recovery of either molten iron, or lower oxides of iron if it is desired to protect such products from reoxidation prior to discharge from slag discharge 16.

By suitably proportioning the dimensions of the cyclone burner and regulating the velocity of gas therein it is possible to operate it with a region adjacent the inlet completely reducing even after the addition of some secondary air and then to add further along the burner tertiary air through inlet 18. When so operated, the heat released by the addition of the tertiary air will be transferred towards the inlet end of the burner very rapidly by radiation and will be available to supply the heat necessary for the reduction of iron compounds. By this procedure the amount of iron capable of being reduced by a given amount of solid fuel is increased. This is an economic advantage where there is a limited outlet for the latent heat of combustion of the gaseous products of the burner.

The cyclone burner may Well be substituted for the conventional sintering process to condition finely divided ores for charging into a blast furnace. Finely divided iron oxides are being produced in increasing quantities by the iron and steel industry. One fruitful source of such material is the fine dust produced in the normal operation of the blast furnace. As the quality of'the iron ores available deteriorates, the amount of flue dust produced per ton of pig iron increases. Most of the beneficiating processes proposed to date for the utilization of ores too lean or siliceous for use in the blast furnace involve the crushing or pulverizing of the ores. Such pulverized products must be sintered or otherwise agglomerated before they can be used. When these pulverulent materials are treated in the cyclone burner, the operation may be conducted at any point on the oxidation-reduction spectrum that may be dictated by local economic conditions. If conducted in an oxidizing atmosphere, the pulverulent material is simply fused without reduction. However, with progressively stronger reducing atmospheres, the ferric compounds may be reduced to magnetite, or to a mixture of magnetite and ferrous oxide or even to elemental iron. As stated above, it is possible to also produce a mixture of reduced oxides and coke which may be directly charged into the blast furnace.

Throughout this specification the cyclone burner has been described as a cylindrical structure slightly inclined to the horizontal. However, it is to be understood that the invention contemplates other positions including horizontal and vertical cylinders.

It is possible to produce an iron of the desired carbon content by regulating the amount of carbon present in the helically flowing slag and by adjusting the time of residence of the reduced iron in the cyclone burner. However the carbon content in the final product is most economically regulated by completely reducing the iron and saturating it with dissolved carbon, and then through a separate opening introducing a stream of crushed iron oxide. This addition serves the double purpose of reducing the carbon content of the melt and reducing the iron oxide to metallic iron and hence enhancing the yield. Similarly, it is possible to produce an alloy of iron and any of the metals no more diflicult to' reduce than iron by the simple expedient of adding the appropriate metal or its compounds to the incoming stream of iron ore. Under some circumstances, substantial amounts of metals more difiicult to reduce than iron may be produced and alloyed with the product. As an example, if conditions Within the burner are established highly reducing and the temperature is maintained well above that necessary to keep the iron in a molten state, silicon will readily reduce from the more siliceous ores.

I claim as my invention:

1. The process of burning solid fuel comprising circulating a coolant in a confined stream within a refractory ed cylindrical container, said coolant being confined in a metallic conduit adjacent the periphery of the container injecting tangenn'ally and at high velocity a highly preheated stream of oxidizing gas into said cylindrical container, adding to said stream of oxidizing gas a crushed solid fuel and a subdivided metalliferous material, the total heat generated by the combustion of the fuel and brought in in the preheated oxidizing gas being sufiicient to liquefy as a slag or metal the metallic reactants and to gasify all of the other products of reaction except the carbon of the fuel, the velocity of the injected stream of oxidizing gas being suflicient to carry with it at least a portion of the liquid products of reaction in a helical path along the interior periphery of the refractory lined cylindrical container, the ratio of solid fuel to oxidizing gas being made sutficiently high to reduce at least a portion of the metallic content of the slag to elemental metal, tapping ofi the molten slag and metal from the periphery of the container, ejecting the highly heated and combustible gaseous products of reaction into a combustion chamber and there burning these gaseous products of combustion with a further addition of oxidizing gas before said gaseous products of combustion have substantially cooled.

2. The process of burning solid fuel comprising circulating a coolant in a confined stream Within a refractory lined cylindrical container, said coolant being confined in a metallic conduit adjacent the periphery of the container injecting tangentially and at high velocity a highly preheated stream of air into said cylindrical container, adding to said stream of air a crushed solid fuel and a subdivided metalliferous material, the total heat generated by the combustion of the fuel and brought in in the preheated air being sufficient to liquefy as a slag or metal the metallic reactants and to gasify all of the other products of reaction except the carbon of the fuel, the velocity of the injected stream of air being sufficient to carry with it at least a portion of the liquid products of reaction in a helical path along the interior periphery of the refractory lined cylindrical container, the ratio of solid fuel to air being made sufiiciently high to reduce at least a portion of the metallic content of the slag to elemental metal, tapping off the moldten slag and metal from the periphery of the container, ejecting the highly heated and combustible gaseous products of reaction into a combustion chamber and there burning these gaseous products of combustion with a further addition of air before said gaseous products of combustion have substantially cooled.

3. The process of burning solid fuel comprising circulating a coolant in a confined stream within a refractory lined cylindrical container, said coolant being confined in a metallic conduit adjacent the periphery of the container injecting tangentially and at high velocity a highly preheated stream of oxidizing gas into said cylindrical container, adding to said stream of oxidizing gas a crushed solid fuel and a subdivided ferruginous material, the total heat generated by the combustion of the fuel and brought in in the preheated oximzing gas being suflicient to liquefy as a slag the metallic reactants and to gasify all of the other products of the reaction except the carbon of the fuel, the velocity of the injected stream of oxidizing gas being sufiiciently high to carry with it at 6 least a portion of the liquid products of reaction in a helical path along the interior periphery of the refractory lined cylindrical container, the ratio of solid fuel to oxidizing gas being made sufficiently high to reduce at least a portion of the iron content of the slad to elemental iron, tapping from the periphery of the container molten slag and molten iron, ejecting the highly heated combustible gaseous products of reaction into a combustion chamber and there burning these gaseous products of combustion with a further addition of oxidizing gas before said gaseous products of combustion have substantially cooled.

4. The process of burning solid fuel comprising circulating a coolant in a confined stream Within a refractory lined cylindrical container, said coolant being confined in a metallic conduit adjacent the periphery of the container injecting tangentially and at high velocity a highly preheated stream of air into said cylindrical container, adding to said stream of air a crushed solid fuel and a subdivided ferruginous material, the total heat generated by the combustion of the fuel and brought in in the preheated air being suflicient to liquefy as a slag the metallic reactants and to gasify all of the other products of the reaction except the carbon of the fuel, the velocity of the injected stream of air being sufficiently high to carry with it at least a portion of the liquid products of reaction in a helical path along the interior periphery of the refractory lined cylindrical container, the ratio of solid fuel to air being made sufiiciently high to reduce at least a portion of the iron content of the slag to elemental iron, tapping from the periphery of the container molten slag and molten iron, ejecting the highly heated combustible gaseous products of reaction into a combustion chamber and there burning these gaseous products of combustion with a further addition of air before said gaseous products of combustion have substantially cooled.

5. The process of burning solid fuel comprising circulating a coolant in a confined stream Within a refractory lined cylindrical container, said coolant being confined in a metallic conduit adjacent the periphery of the container injecting tangentially and at high velocity a highly preheated stream of oxidizing gas into said cylindrical container, adding to said stream of oxidizing gas a crushed solid fuel and a subdivided ferruginous material, the total heat generated by the combustion of the fuel and brought in in the preheated oxidizing gas being suflicient to liquefy as a slag the metallic reactants and to gasify all of the other products of the reaction except the carbon of the fuel, the velocity of the injected stream of oxidizing gas being sufficient to carry with it at least a portion of the liquid products of reaction in a helical path along the interior periphery of the refractory lined cylindrical container, the ratio of solid fuel to oxidizing gas being made at least sufficiently high to produce from the ferruginous material a substantial portion of the low melting eutectic or ferric and ferrous oxides, tapping from the periphery of the container said eutectic mixture of ferrous and ferric oxides as a slag, ejecting the highly heated and combustible gaseous products of the reaction from the cyclone burner and burning these gaseous products of combustion with a further addition of oxidizing gas.

6. The process of burning solid fuel comprising circulating a coolant in a confined stream within a refractory lined cylindrical container, said coolant being confined in a metallic conduit adjacent the periphery of the container injecting tangentially and at high velocity a highly preheated stream of oxidizing gas into said cylindrical container, adding to said stream of oxidizing gas a crushed solid fuel and a subdivided metalliferous material, the total heat generated by the combustion of the fuel and brought in in the preheated oxidizing gas being suificient to liquefy as a slag or metal the metallic reactants and to gasify all of the other products of reaction except the carbon of the fuel, the velocity of 7 the injected stream of oxidizing gas being sufficient to carry with it at least a portion of the liquid products of reaction in a helical path along the interior periphery of the refractory lined cylindrical container, the ratio of solid fuel to oxidizing gas being made sufficiently high to reduce at least a portion of the metallic content of the slag to elemental metal, tapping ofi the molten slag and metal, ejecting the highly heated and combustible gaseous products of reaction from the cylindrical container and burning these gaseous products of combustion with further addition of air.

' 7. The process of burning solid fuel comprising circulating a coolant in a confined stream within a refractory lined cylindrical container, said coolant being confined in a metallic conduit adjacent the periphery of the container injecting tangentially and at high velocity a highly preheated stream of oxidizing gas into said cylindrical container, adding to said stream of oxidizing gas a crushed icokable solid fuel and a subdivided ferruginous material, the total heat generated by the combustion of the fuel and brought in in the preheated oxidizing gas being sufficient to liquefy as a slag the metallic reactants and to gasify all of the other products of the reaction except the carbon of the fuel, the velocity of the injected stream of oxidizing gas being sufficient to carry with it at least a portion of the liquid products of reaction in a helical path along the interior periphery of the refractory lined cylindrical container, the ratio of solid fuel to oxidizing gas being made at least sufficiently high to produce from the ferruginous material a substantial portion of the loW melting eutectic of ferric and ferrous oxides and to leave a residue of unburned coke, tapping from the periphery of the container said eutectic metastable mixture of ferrous and ferric oxides and coke as a slag, ejecting the highly heated and combustible gaseous products of the reaction from the cyclone burner and burning these gaseous products of combustion with a further addition of oxidizing gas.

8. The process of burning solid fuel comprising circulating a coolant in a confined stream within a refractory lined cylindrical container, said coolant being confined in a metallic conduit adjacent the periphery of the container injecting tangentially and at high velocity a highly preheated stream of oxygen enriched air into said cylindrical container, adding to said stream of oxygen enriched air a crushed solid fuel and a subdivided metalliferous material, the total heat generated by the cornbustion of the fuel and brought in in the preheated oxygen enriched air being suflicient to liquefy as a slag or metal the metallic reactants and to gasify all of the other products of reaction except the carbon of the fuel, the velocity of the injected stream of oxygen enriched air being sufficient to carry with it at least a portion of the liquid products of reaction in a helical path along the interior periphery of the refractory lined cylindrical container, the ratio of solid fuel to oxygen enriched air being made sufi'iciently high to reduce at least a portion of the metallic content of the slag to elemental metal, tapping off the molten slag and metal, ejecting the highly heated and combustible gaseous products of reaction from the cylindrical container and burning these gaseous products of combustion with further addition of air.

9. The process of burning solid fuel comprising circulating a coolant in a confined stream within a refractory lined cylindrical container, said coolant being confined in a metallic conduit adjacent the periphery of the container injecting tangentially and at high velocity a highly preheated stream of oxygen enriched air into said cylindrical container, adding to said stream of oxygen enriched air a crushed solid fuel and a subdivided ferruginous material, the total heat generated by the combustion of the fuel and brought in in the preheated oxygen enriched air being sufficient to liquefy as a slag the metallic reactants and to gasify all of the other products 8 of the reaction except the carbon of the fuel, the velocity of the injected stream of oxygen enriched air being sufiiciently high to carry with it at least a portion of the liquid products of reaction in a helical path along the interior periphery of the refractory lined cylindrical container, the ratio of solid fuel to oxygen enriched air being made sufficiently high to reduce at least a portion of the iron content of the slag to elemental iron, tapping from the periphery of the container molten slag and molten iron, ejecting the highly heated combustible gaseous products of reaction into a combustion chamber and there burning these gaseous products of combustion with a further addition of oxygen enriched air.

10. The process of burning solid fuel comprising circulating a coolant in a confined stream Within a refractory lined cylindrical container, said coolant being confined in a metallic conduit adjacent the periphery of the container, injecting tangentially and at high velocity a stream of air into said cylindrical container, adding to said stream of air a crushed, solid fuel and a sub-divided ferruginous material, the total heat generated by the combustion of the fuel and brought in in the air stream being sufiicient to liquefy as a slag the metallic reactants and to gasify all of the other products of the reaction except the carbon of the fuel, the velocity of the injected stream of air being sufficient to carry with at least a portion of the liquid products of the reaction in a helical path along the interior periphery of the refractory lined cylindrical container, tapping from the periphery of the container molten ferruginous material and ejecting the highly heated gaseous products of reaction from the refractory lined cylindrical container.

ll. The process of burning solid fuel comprising circulating a coolant in a confined stream within a refractory lined cylindrical container, said coolant being confined in a metallic conduit adjacent the periphery of the container, injecting tangentially and at high velocity a highly preheated stream of air into said cylindrical container, adding to said stream of air a crushed solid fuel and a subdivided ferruginous material, the total heat generated by the combustion of the fuel and brought in in the preheated air being sufficient to liquefy as a slag the metallic reactants and to gasify all of the other products of the reaction except the carbon of the fuel, the velocity of the injected stream of air being sufficiently high to carry with it at least a portion of the liquid products of reaction in a helical path along the interior periphery of the refractory lined cylindrical container, the ratio of solid fuel to air being made sufficiently high to reduce at least a portion of the iron content of the slag to elemental iron and to substantially saturate said iron with carbon, injecting into said carbon saturated iron oxidic ferruginous material to reduce the carbon content of the iron to the desired level, tapping from the periphery of the container molten slag and molten iron, ejecting the highly heated combustible gaseous products of reaction into a combustion chamber and there burning these gaseous products of combustion with a further addition of air before said gaseous products of combustion have substantially cooled.

12. The process of burning solid fuel and producing an alloy of iron with a metal more dif cultly reducible than iron comprising circulating a coolant in a confined stream within a refractory lined cylindrical container, injecting tangentially and at high velocity a highly preheated stream of air into said cylindrical container, adding to heated stream of air a crushed solid fuel, a ferruginous material and a metaliiferous material containing a metal more difiiculty reducible than iron, the total heat generated by the combustion of the fuel and brought in the preheated air being sufficient to liquefy all of the products of the reaction except the carbon of the fuel, the velocity of the injected stream of air being sufliciently to carry with it at least a portion of the liquid products of reaction in a helical path along the interiorperiphcry of the refractory lined cylindrical, container, the ratio of solid fuel to air being made sufliciently high to reduce substantially all of the iron and the more diflicultly reducible metal, tapping from the periphery of the container molten slag and molten alloyed iron, ejecting the highly heated combustible gaseous products of reaction into a 5 combustion chamber and there burning these gaseous products of combustion with a further addition of air before said gaseous products of combustion have substantially cooled.

References Cited in the file of this patent UNITED STATES PATENTS McNamara Mar. 5, 1907 Delavel July 30, 1907 Kapteyn Apr. 8, 1924 Schmalfeldt Feb. 8, 1938 Bailey et a1. Sept. 5, 1944 

1. THE PROCESS OF BURNING SOLID FUEL COMPRISING CIRCULATION A COOLANT IN A CONFINED STREAM WITHIN A REFRACTORY LINED CYLINDRICAL CONTAINER, SAID COOLANT BEING CONFIRNED IN A METALLIC CONDUIT ADJACENT THE PERIPHERY OF THE CONTAINER INJECTING TANGENTIALLY AND AT HIGH VELOCITY A HIGHLY PREHEATED STRAM OF OXIDIZING GAS INTO SAID CYLINDRICAL CONTAINER, ADDING TO SAID STREAM OF OXIDIZING GAS A CRUSHED SOLID FUEL AND A SUBDIVIDED METALLIFEROUS MATERIAL, THE TOTAL HEAT GENERATED BY THE COMBUSTION OF THE FUEL AND BROUGHT IN IN THE PREHEATED OXIDIZING GAS BEING SUFFICIENT TO LIQUEFY AS A SLAG OR METAL THE METALLIC REACTANTS AND TO GASIFY ALL OF THE OTHER PRODUCTS OF REACTION EXCEPT THE CARBON OF THE FUEL, THE VELOCITY OF THE INJECTED STREAM OF OXIDIZING GAS BEING SUFFICIENT TO CARRY WITH IT 